I’ll second all of what Ali said, but I’d also like to add that not all games these days even allow homemade darts due to safety concerns. The worst-case here would be a felt tip falling off and exposing the metal washer underneath.

For this reason some darts were made without a washer at all - and with either a solid lump of hotglue serving as the weighted tip or with a small BB in the bottom of that hole for weight (which guide Ali linked might already say? There’s a follow-up post saying that it was updated to include metal-free dart tips but I can’t find where it describes how to make them.)

OP, I’d recommend reconsidering whether you want a hard tip. If you’re running into issues with people not feeling and not taking hits, improving the velocity of your blaster will solve that while also providing greater range a difficulty-to-dodge. (If your problem is people “not feeling” and not taking hits - then that’s not something that any modification can solve short of something actually dangerous.)

If you do have a good reason for wanting a harder-than-normal tip, then 3d printed tips are an option. TPU is available in a variety of hardnesses and differing infill and tip geometry should theoretically allow you to design a tip with whatever characteristics you want. I wouldn’t recommend this - most people don’t other with homemade darts at all any more and there’s good reasons for that - but it is an option if you just want homemade darts.